Recommendations on the measurement and use of the alcohol consumption biomarker CDT. A position paper from the IFCC Working Group on CDT standardisation.

BACKGROUND: Carbohydrate deficient transferrin (CDT) is a biomarker for excessive alcohol consumption utilized in clinical and forensic medicine and workplace testing. Previously, many different analytical methods for CDT were used and the measurand varied considerably, making direct comparison of test results difficult. To end this confusion, the IFCC established a working group on CDT standardisation (WG-CDT) which completed its tasks in 2017. METHODS: This IFCC position paper by the WG-CDT summarizes state of the art information about the measurand and the analytical methods and gives concise recommendations for its utilization. RESULTS: The results achieved by the CDT standardisation process led to accuracy improvements in national external quality assessment schemes over the years. A brief review of ROC based comparison studies with the traditional biomarkers (GGT, MCV, ALT and AST) discusses the bias resulting from inadequate study populations. In large groups of the general population the superior diagnostic performance of CDT is confirmed. CONCLUSION: The relationship between alcohol intake versus resulting CDT is discussed as well as the cutoff and measurement uncertainty. Concerning the application in practice, potential pitfalls are considered and recommendations handling both analytical and preanalytical caveats are given. Finally, some examples of serious misunderstandings in publications about CDT are addressed.

Capillary electrophoresis system for hemoglobin A1c determinations evaluated.

Hb A1c is the analyte of choice for monitoring metabolic control in patients with diabetes mellitus. Here we present a new analytical technique for measuring Hb A1c, capillary electrophoresis. The Hb A1c determination is not influenced by the labile Hb A1c fraction or by carbamylated or acetylated hemoglobin derivatives. Also, hemoglobin variants (Hb F, Hb S, and Hb C) do not interfere. This new application of capillary electrophoresis seems to be a valuable analytical tool for measuring Hb A1c in the clinical laboratory.

Interference of carbamylated and acetylated hemoglobins in assays of glycohemoglobin by HPLC, electrophoresis, affinity chromatography, and enzyme immunoassay.

In vitro-synthesized carbamylated and acetylated hemoglobins interfered in assays of glycohemoglobin by HPLC and electrophoresis but had no effects on results obtained by affinity chromatography and enzyme immunoassay. Correlations between long-term serum urea concentrations and glycohemoglobin percentages revealed that, in vivo, carbamylated hemoglobin equivalent to 0.063% of total hemoglobin is formed for every 1 mmol/L of serum urea. The use of acetylsalicylate, either chronically in small doses (200-300 mg/day) or for 1 week at 2000 mg/day, did not cause significant interference from acetylhemoglobin, formed in vivo. We conclude that interference from carbamylated hemoglobin explains only a small part of existing discrepancies between results of glycohemoglobin assays in current use. The interfering effect of acetylhemoglobin formed in vivo with acetyl-CoA as substrate is as yet unknown.